Air preheater



March 20, 192-8.

' P. THOMSEN AIR PREHEATER Filed Jan.16, 1925 l air Zfi mJen/INVENTO 14 A TTORNEV Patented Mar. 20, 1928.

hair-a stares weasel nest es.

IPETER'THOMSEN, 0-15 CASSEL, GERMANY, ASSIGNOR TO THE SUPERHEATER COMPANY, OF'NEW YORK, N. Y.,' A CORPORATION OF DELAWARE.

AIR PREHEATER.

Application filed January 16,1925, Serial No. 2,774, and in Germany March '3, 1924..

The subject of the present invention is a boiler for'movable steam power'installation, finding application particularly in connection with locomotives.

According to the invention an air preheateris built intoa boiler in'su'ch a manner that the longitudinal axis of the preheater extends substantially in an up'and down di- .rection, and the air is supplied to the "air .preheater through an opening in the upper part'of the front wall of the'smoke box. The preheater preferably comprises parallel pipes. Contrary to known-arrangements of air 'preheaters which lie entirely or for their greatest part in the lower part 'ofthe smoke chamber'and have 'an'air supply opening which is arranged 'at'the'lower part of the front wall of'the smoke chamber, the present arrangement presents the advantage that during the motion'of the boiler the air can enter better and with less disturbance than if the supply opening for the air is atthe lower part ofthe' front wall of the smokebox, as in the latter position of the air op'eningthe airis diverted upwardly. In connection with the use of'an air preheater according to the present invention, a boiler of any preferred form may be used. For example, the boiler can 'beshortened to such an extent that there is still sufficient best left at the exit of the hot'gas'es from the fines, and before these hot gases are allowed to come into contact with the preheater so that the steam can be raised to the desired degree of superheat in av superheaterv which is removable either upwardly or laterally. However, a superheater may also be chosen which can be removed through the smokebox after the manner of a smoke tube superheater, or which can be constructed according to the usual form of smoke tube superheater. In this "case the air preheater must be so arranged that it can be removed out of "the direct path of the superheater elements. 7 In the drawings thereare represented different illustrative'forms of boilers according to this invention.- Figurel shows -the smokebox of a 'firetube "boiler with an air p'reheater and witha s'uper'heat'er 'whichlatter can be removed in an upward direction,

this saperheate'r lying between the front tube the boiler and the air preheat'er;

rated smokebox an air preheater 5, consisting of parallel tubes, is arranged so 'that its general direction is diagonallydownwardzfrom front to rear. In the upper "portion'of'the front wall of the smokebox there is provided an opening 6 from which -aichannel 7 leads'to the 'airpreheater 5. The channel 7 surrounds the stack '8. The dimensions of the channel 7 "are so chosen thattheiopen ing (Sat the'front wall of the smokebox is materially larger than the opening of the channel leading to thepreheater 5 sothat a sort of funnel is formed. 'Therainflows in through-the channel 7, as indicated-by the arrowfflows next through thepreheater 5, and then through the channel 9, whichlies below the boiler and carries the an: to a'point below the grate.

The shortening o'f-theboiler 2 and 0f the boiler tubes 3 is so calculated that-thexhot gases leave the tubes'at a temperature still high enough" thateven after the requisiteheat is abstracted for superheating thesteamin a superheater 1O located between'the smokebox end of the boiler and'the preheater -5 there is'suflicient heat left "to preheat the air flowing through the preheater to-the desired temperature. The superheater :10, to which saturated steam from'theboiler is delivered by pipe 11, is in-the'illustrative exampleso arranged that it can be taken out upwardly from thesmok'ebox through an opening 12, which is normally'olosedbut can be opened for this purpose. The-superheater can also be soarra'nged that'itqcan be removed laterally from the smokebox. The best arrangement for the lsuperheater is such that the steam which istobe;-superheated flows through it' ina directiomcounter to that in which the hot gases arewmove ing. In the illustrative example thesatusteam. is thereforemad'eto enter the zle 16.

WVhile in the arrangement according to Figure 1 the air preheater ispermanently built in and. the superheater may be removed either upwardly or laterally, provision must be made in those types of superheaters which are removable through the smokeboX so that the air preheater may superheater elements.

readily be removed out of the path of the This is done in the forms givenby way of illustration in Figures 2 and 3.

In Figure 2 the. smol rebox 4 is again equipped at its upper portion with an opening 6. through which the channel 7 leads to the upper end'of the air preheater 5. The

latter is so arranged that its tubes lie in a I vertical position and that it may be integralremoved upwardly from the smokebox through the normally'closed opening 17.

The cover B is made removable for this purpose. The deflecting plate A is preferably secured directly to cover B so the two are removed'together. The air which enters at the opening 6 in this case also flows around the stack 8 while passing through the channel 7, and after it has passed through the preheater 5 reaches the duct 9 and thence the grate. In the duct 9 there is arranged in Figure 2 a sort of hopper 18, through which cinders carried along by the hot gases can be removed. This hopper 18 is surrounded by the air flowing through the In this case the boiler consists of an upper steam chamber 19 and-of lateral steam and 'water chambers 20, which together form an upper and two lateral walls.

The chambers are connected by cross pipes 21. In the intermediate spaces left free by these cross pipes there are located the serpentine elements 22 of a superheater whose saturated and superheated headers are respectively numbered 23 and 24. If it is desired to remove any of the elements 22 through the smokebox or to insert them, the air preheater 5 must first be removed upwardly through the opening 17 In Figure 3 there is represented a fire tube boiler 2 with fire tubes 3, which is equipped with a smoke tube superheater of the usual type in which the serpentine elements 25 lie in the smoke tubes and open into a common header 26. The smokebox 4 again has the opening 6 in the upper part of the front wall through which air flows into the channel 7 to flow thence through the tubes of the air preheater 5, after which itis carriedto a point below the grate through the duct- 9.

The tubes 5 lie in a diagonal direction from the front rearward and downward. The air preheater 5 is in this case so arranged that it can be rotated about the axis 27 into'the approximately horizontal position indicated by the dotted lines. In the normal position indicated by full lines it is held by means of a latch or the like 28 and 29, or in any other desired manner. This is shown on an enlarged scale and more clearly in Fig. 3. When the air heater is in its normal position, the latch 28 engages the angle iron E which latch 28 is moved out of engagement with E,

and the heater is lowered by means of the cable G, which 1s secured toone or more of is secured to the upper end of the heater by the tubes and is wound on the drum C.

The crank D'for rotating drum lies outside of the smokebox. In this case also the air preheater 5 is removed out of the path smokebox, but may be simply rotated down I into the dotted position. a

By means of the arrangement described and illustrated of a boiler with a preheater lying in the smokebox, there can in all cases be obtained a sufficient preheating of. the combustion air and suflicient heat will be re moved from the waste gases. Generally it will. be suflicient if the temperature of the combustion air is raised to about C. Assuming by way of illustration that the desired superheated steam temperature is to be 350 C; then the gases leaving the superheater will-have an approximate temperature of 850 C. and can give'up approximately 100 C. to the air flowing through the air preheater so that they will reach the stack with a temperature of about 250 C. In practicing the invention according to Figure 1 in which the smoke tubes are shortened, thearrangement will be such that the gases will leave the flues with a temperature of approximately 500 to 550 C. and come into contact with thesuperheater at such a temperature. Here they give upto the steam which is to be superheated approximately 200 C. so that they-will leavethe superheater for the air preheater at about 350? C., give up to. the air passingthrough it about 100 C. and pass on to the stack at about 250 C. been described and shown and in all similar cases which fall within the scope of this in- In all ofthe cases which have vention there is therefore obtained a par-' ticularly economical utilization of the heat of the gases, together with the desired amount of superheating and of the preheating of the combustion air.

If desired the shortening of the boiler can be carried even further so thatin addition to superheating the live steam and preheating the combustion air the hot gases leave the boiler at an even higher temperature and can be used to reheat the steam in an intermediate reheater as it flows from one stage of the engine to the next. In Figure 4: an illustrative case of a boiler of this type is shown in which this is made possible. As in the form according to Figure 2, the boiler here also consists of uppenchambers 19, lower chambers 20 and cross tubes 21 connecting them. The superheater which superheats the live steam is arranged in the smokebox beyond the boiler and can, as in the case of Figure 1, be removed through the normally closed opening 12. The superheater here also as in Figure 1 comprises the distributing header 13 (which receives steam from the boiler through pipe 11) and the superheater elements 10 from which the steam flows at 14: to be delivered into the superheated chamber 15 whence it is carried to the high pressure stage of the engine. In addition to this live steam superheater an intermediate reheater consisting of serpentine tubes 30 is arranged in the smokebox beyond it. This reheater can also be removed through the opening 12. The steam which is to be reheated enters the chamber 31 and flows also in a direction counter to the heating gases through the elements 30 to the chamber 32 whence it flows to the next stage of the engine.

In Figure' l there is also shown a variation of the form of the air preheater. Its tubes 5 extend vertically downward from the horizontal inner end of the channel 7 and then turn at right angles into the vertical partition at the front end of duct 9. Since the two superheaters can be removed upwardly it is not necessary in this case to make provision for ready removal of the air preheater. This form of the air preheater with the curved pipe ends has the advantage that no cinders can lodge on the tube sheet to which the pipes are secured at the end opening into the air duct. p

In Figure 5 there is shown a special form of an air preheater of the kind indicated in Figure 4:, the heater being viewed from the front, The lower ends of the pipe 5 are so arranged that, viewed in the direction of ing gases withthe greatest possible amount of heating surface.

The air preheater which is represented in Figure 4 could be made out of plates in a previously known manner which would take the place of the pipes.

What I claim is:

1. In a locomotive boiler, the combination of a smokebox into which gases are discharged from the boiler Hues, a stack extending through the forward upper part of the smokebox sheet, an intake for air at the upper part of the front wall of the smokebox, a. passage extending rearwardly from the intake and surrounding the stack, an air preheater comprising two parallel tube sheets and tubes connecting them, a

duct extending rearwardly from the lower part of the smokebox, the air preheater extending from the rear end of said passage to the front end of said duct, superheater elements extending into said flues, said preheater being hinged at its lower end so it can be rotated out of the direct line ofsaid elements, and means. to hold the preheater in its normal operative position.

2. In a locomotive boiler equipped with tubular superheaterelements extending into the boiler from the smokebox, the combination of said smoke-box; anintake for air at the upper part of the front wall of the smoke-box; an air preheater comprisingtwo tube sheets and tubes connecting them; a duct extending rearwardly from the lower part of the smoke-box; the air preheater being arranged in front of said superheater elements and receiving air from the intake and discharging it into the duct; and the air preheater being readily removable as a unit out of the direct line of said superheater elements. 7

PETER THOMSEN. 

